How it works

Spell Resistance is both a stat and a skill. The stat is based on the characters Willpower stat (so if a player has a willpower of 200, they will have a base Spell Resistance of 200 before any other mods are factored in), and it can be increased by a number of means (the +% Spell Resistance mod on items, either native on the item, or forged into items). Spell Resistance is used in a calculation with Spell Intensity (the defender's Spell Resistance v the attacker's Spell Intensity), if the defender "wins" or "succeeds" on this calculation, the attacker's spell's damage is reduced by a % (possibly 30%), if the attacker "wins", their spell damage is not reduced at this point (though it will still be reduced by any resistance or elemental mitigation).

This diagram shows, how the strength of Secondary Damage Effects decreases with each new attribute point, invested in willpower.
The graph depends on character level. Its curve is always the same, but the scales on the axis differ.

The beginning of the graph (when willpower does not affect DMEs, equal to 100% strength of DMEs) depends on character level, according to the following formula: